Lydia A. Shrier, M.D., M.P.H., is an Adolescent Medicine specialist committed to a career in patient-oriented clinical research. Her research goals are to develop and evaluate adolescent-specific interventions to reduce sexual risk behavior and sexually transmitted diseases (STDs), including human immunodeficiency virus (HIV) infection. Adolescents are the population at highest risk for STD/HIV. Studies have suggested that mental health problems, including depression, low self-esteem, and low self-efficacy, may play an important role in the development of sexual risk behaviors and influence the effectiveness of STD/HIV prevention interventions. To develop effective STD/HIV risk reduction interventions for adolescents, it is critical to understand the impact of poor mental health on sexual risk behavior. A K23 Award would provide Dr. Shrier with the funding and time to pursue intensive training in health behavior and interventional trial design, implementation, and analysis, as well as to acquire new knowledge and experience in the study of mental health and sexual risk behavior. The superb clinical, research, and teaching faculties of Children's Hospital, Boston, Harvard Medical School, and Harvard School of Public Health will support Dr. Shrier in meeting the objectives of the career development and research plans. The Career Development Plan includes (1) coursework in biostatistics and research design, (2) a fellowship with the Behavioral Interventions and Research Branch of the Division of STD Prevention at the Centers for Disease Control and Prevention, (3) mentoring in mental health research, prevention/intervention theory and methodology, and health behavior research, and (4) on-going access to consultation and support during the planning, implementation, and evaluation of the proposed research. The Research Plan proposes 3 linked studies to evaluate the hypothesis that depression, low self-esteem, negative mood, and low self-efficacy to use condoms are related to condom nonuse and STD acquisition among sexually active adolescents. Study 1 will use data from the National Longitudinal Survey of Adolescent Health to evaluate associations of depressive symptoms and self-esteem with condom nonuse and STD acquisition. Informed by Study 1, Studies 2 and 3 will prospectively examine associations of these mental health risk factors, as well as mood and self-efficacy to use condoms, with outcomes of inconsistent condom use and STD acquisition in a randomized clinical trial of an interactive video-plus-counseling safer sex intervention. An objective biologic measure, Chlamydia trachomatis infection, as well as self-reported condom use will be used to assess intervention effectiveness. Study 2 will use the control group to elucidate temporal relationships among the mental health factors and the outcomes of condom nonuse and Chlamydia acquisition over one year. Study 3 will evaluate whether poor mental health alters response to the intervention, as measured by a reduction in Chlamydia incidence. If mental health is found to influence intervention effectiveness, the results of the study will be used to develop a program that systematically incorporates mental health evaluation and treatment into the prevention of HIV and other STDs in adolescents.